Airfoil trailing edge

ABSTRACT

An airfoil includes a radially inner edge extending in a radial direction of the airfoil to a radially outer edge. Also included is a leading edge extending in an axial direction of the airfoil to a trailing edge. Further included is a trailing edge geometry comprising at least one wave segment having simultaneous curvature in at least two directions.

BACKGROUND OF THE INVENTION

The subject matter disclosed herein relates to airfoils, and moreparticularly to trailing edge regions of airfoils for use in gas turbineengines.

In gas turbine engines, such as industrial and aircraft systems,compressor blade failure is an important concern. One reason for bladefailure relates to wake shed by upstream struts and stator vanes on thedownstream blades. The wake creates unsteady pressure load on the bladesand if the frequency of the wake matches with the natural frequency ofthe blades, the failure can be significant. Therefore, wake strengthreduction is a common goal in gas turbine engine industries.

BRIEF DESCRIPTION OF THE INVENTION

According to one aspect of the invention, an airfoil includes a radiallyinner edge extending in a radial direction of the airfoil to a radiallyouter edge. Also included is a leading edge extending in an axialdirection of the airfoil to a trailing edge. Further included is atrailing edge geometry comprising at least one wave segment havingsimultaneous curvature in at least two directions.

According to another aspect of the invention, a compressor includes anairfoil. Also included is a trailing edge of the airfoil. Furtherincluded is a trailing edge geometry comprising a plurality of wavesegments including a first wave segment having a degree of curvature inan axial direction and a second wave segment having a degree ofcurvature in a circumferential direction.

According to yet another aspect of the invention, a gas turbine engineincludes a compressor section. Also included is a turbine section.Further included is an airfoil disposed in at least one of thecompressor section and the turbine section, the airfoil having atrailing edge comprising a geometry having at least one wave segmentincluding simultaneous curvature in an axial direction and in acircumferential direction.

These and other advantages and features will become more apparent fromthe following description taken in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The subject matter, which is regarded as the invention, is particularlypointed out and distinctly claimed in the claims at the conclusion ofthe specification. The foregoing and other features, and advantages ofthe invention are apparent from the following detailed description takenin conjunction with the accompanying drawings in which:

FIG. 1 is a schematic illustration of a gas turbine engine;

FIG. 2 is a partial perspective view of an inlet of a compressor sectionof the gas turbine engine;

FIG. 3 is a schematic illustration of the inlet of the compressorsection;

FIG. 4 is a side, elevational view of the compressor section;

FIG. 5 is a perspective view of an airfoil according to a firstembodiment;

FIG. 6 is a side, elevational view of the airfoil according to theembodiment of FIG. 5;

FIG. 7 is a side, elevational view of the airfoil according to a secondembodiment; and

FIG. 8 is a schematic illustration of various geometries of a portion ofthe airfoil.

The detailed description explains embodiments of the invention, togetherwith advantages and features, by way of example with reference to thedrawings.

DETAILED DESCRIPTION OF THE INVENTION

The terms “axial” and “axially” as used in this application refer todirections and orientations extending substantially parallel to a centerlongitudinal axis of a turbine system. The terms “radial” and “radially”as used in this application refer to directions and orientationsextending substantially orthogonally to the center longitudinal axis ofthe turbine system. The terms “upstream” and “downstream” as used inthis application refer to directions and orientations relative to anaxial flow direction with respect to the center longitudinal axis of theturbine system.

Referring to FIG. 1, a turbine system, such as a gas turbine engine 10,constructed in accordance with an exemplary embodiment of the invention,is schematically illustrated. The gas turbine engine 10 includes acompressor section 12, a combustor section 14, a turbine section 16, ashaft 18 and a fuel nozzle 20. It is to be appreciated that oneembodiment of the gas turbine system 10 may include a plurality ofcompressor sections 12, combustor sections 14, turbine sections 16,shafts 18 and fuel nozzles 20. The compressor section 12 and the turbinesection 16 are coupled by the shaft 18. The shaft 18 may be a singleshaft or a plurality of shaft segments coupled together to form theshaft 18.

Referring now to FIG. 2, a partial, cut-away view illustrates an inlet22 of the compressor section 12. FIG. 3 schematically illustrates theinlet 22 of the compressor section 12. The inlet 22 generally refers toa region configured to route an incoming airflow to the compressorsection 12 and comprises a compressor bell mouth 24. Half of thecompressor bell mouth 24 has been removed in FIG. 2 to illustratevarious vanes and blades disposed at an interior region of thecompressor section 12, relative to a compressor section casing 26. Thecompressor bell mouth 24 includes an outer surface 28 and an innersurface 30, with the incoming airflow passing between these twosurfaces. Typically, a plurality of support members 32 are operativelycoupled to the outer surface 28 and the inner surface 30 for support. Asshown in FIG. 3, the inlet 22 includes a strut 33 for supporting thestructures and guiding the incoming airflow prior to passing over aplurality of inlet guide vanes (IGVs) 34.

Referring to FIG. 4, the plurality of IGVs 34 is arranged in acircumferentially spaced manner in what is referred to as a stage.Downstream of one or more stages of the plurality of IGVs 34 are aplurality of rotor blades and a plurality of stator vanes. The statorvanes are generally fixed to a stator or a compressor section casing 26,while the rotor blades are connected to the shaft 18. The plurality ofIGVs 34 is generally fixed as well, but may pitch around a radial axisto vary the direction or amount of incoming flow. The plurality of IGVs34 is followed by a first stage of rotor blades 36, which is in turnfollowed by a first stage of stator vanes 38. Disposed downstream of thefirst stage of stator vanes 38 is a second stage of rotor blades 40,which is followed by a second stage of stator vanes 42. It can beappreciated that the compressor section 12 may include varying numbersof stages of rotor blades and stator vanes, depending on the particularapplication.

Referring to FIGS. 5 and 6, an airfoil 50 is shown and represents any ofthe above-described compressor section airfoils. In particular, theairfoil 50 may be the strut 33, one of the plurality of IGVs 34, and/orthe stator vanes. Although illustrated and described in accordance withairfoils of the compressor section 12 and the inlet 22, it is to beappreciated that airfoils in other parts of the gas turbine engine 10,such as the turbine section 16, may benefit from the embodiments of theairfoil 50 described below.

The airfoil 50 extends predominantly in an axial direction 52 from aleading edge 54 to a trailing edge 56, although curvature of the airfoil50 is common The airfoil 50 is defined in a radial direction 58 by aradially inner edge 60 and a radially outer edge 62. In order tomitigate wake strength proximate regions downstream of the trailing edge56, a trailing edge geometry 64 is formed along the trailing edge 56.The trailing edge geometry 64 comprises a multi-dimensional wavegeometry that includes waves having curvature in multiple directions. Inparticular, the trailing edge geometry 64 is formed of at least one, buttypically a plurality of wave segments 68 having simultaneous curvaturein at least two directions. In the illustrated embodiment, the pluralityof wave segments 68 includes simultaneous curvature in both the axialdirection 52 and a circumferential direction 70. In other words, as eachof the plurality of wave segments 68 curve in one direction (i.e.,axially or circumferentially), simultaneous curvature in anotherdirection is made.

Varying degrees of curvature may be employed in different embodiments,depending on the particular flow characteristics of the particularapplication. As shown in FIG. 8, the axial angle of curvature θ orindentation of the plurality of wave segments 68 may vary. In oneembodiment, the angle of curvature θ ranges from about 45° to about 80°.The plurality of wave segments 68 shown in the embodiment of FIGS. 5 and6 are radially oriented toward the radially outer edge 62. However, inan alternative embodiment, a portion of the plurality of wave segments68 are radially oriented toward the radially outer edge 62, while aportion of the plurality of wave segments 68 are radially orientedtoward the radially inner edge 60 (FIG. 7). In yet another embodiment,all of the plurality of wave segments 68 are radially oriented towardthe radially inner edge 60. As shown, the number of wave segments mayvary. Regardless of whether all or a portion of the plurality of wavesegments 68 are radially oriented in a direction, the radial angle α oforientation may vary (FIG. 8). In one embodiment, the radial angle αranges from about 0° to about 35°.

In an alternative embodiment, the plurality of wave segments 68comprises an alternating arrangement of wave segments. The alternatingarrangement refers to a circumferentially curved wave segment followedby an axially curved wave segment, or vice versa. This arrangement isrepeated along all or a portion of the trailing edge 56.

Regardless of the precise configuration of the trailing edge geometry64, the plurality of wave segments 68 enhance flow mixing prior torouting of the airflow to regions downstream of the airfoil 50.Efficient flow mixing reduces the effect of wake shed by the airfoil 50,thereby reducing an unsteady pressure load on downstream blades.Exemplary airflow patterns facilitating flow mixing are illustrated inFIGS. 6 and 7 and are referenced with numeral 80. In addition toenhancing blade life, the wake strength reduction assists in having areduced axial gap between various components, thereby reducing theoverall axial length of the gas turbine engine 10, and in particular theinlet 22 of the compressor section 12 for embodiments of airfoilsdisposed in the inlet 22 and/or the compressor section 12. For example,as shown in FIG. 3, an inlet casing length 82, an inlet outer diametercasing length 84, a strut length 86, a strut to IGV length 88, and aflange to the first rotor stage 90 may all benefit from a reduction inaxial length with the embodiments of the airfoil 50 describe above.

While the invention has been described in detail in connection with onlya limited number of embodiments, it should be readily understood thatthe invention is not limited to such disclosed embodiments. Rather, theinvention can be modified to incorporate any number of variations,alterations, substitutions or equivalent arrangements not heretoforedescribed, but which are commensurate with the spirit and scope of theinvention. Additionally, while various embodiments of the invention havebeen described, it is to be understood that aspects of the invention mayinclude only some of the described embodiments. Accordingly, theinvention is not to be seen as limited by the foregoing description, butis only limited by the scope of the appended claims.

1. An airfoil comprising: a radially inner edge extending in a radialdirection of the airfoil to a radially outer edge; a leading edgeextending in an axial direction of the airfoil to a trailing edge; and atrailing edge geometry comprising at least one wave segment havingsimultaneous curvature in at least two directions.
 2. The airfoil ofclaim 1, wherein the at least two directions comprises the axialdirection and a circumferential direction.
 3. The airfoil of claim 2,wherein the at least one wave segment comprises a plurality of wavesegments.
 4. The airfoil of claim 3, wherein at least one of theplurality of wave segments is radially oriented toward the radiallyinner edge and at least one of the plurality of wave segments isradially oriented toward the radially outer edge.
 5. The airfoil ofclaim 3, wherein each of the plurality of wave segments are radiallyoriented toward the radially outer edge.
 6. The airfoil of claim 3,wherein each of the plurality of wave segments are radially orientedtoward the radially inner edge.
 7. The airfoil of claim 2, wherein theairfoil comprises a strut disposed in a compressor inlet region of a gasturbine engine.
 8. The airfoil of claim 2, wherein the airfoil comprisesa stator vane disposed in a compressor section of a gas turbine engine.9. A compressor comprising: an airfoil; a trailing edge of the airfoil;and a trailing edge geometry comprising a plurality of wave segmentsincluding a first wave segment having a degree of curvature in an axialdirection and a second wave segment having a degree of curvature in acircumferential direction.
 10. The compressor of claim 9, wherein theplurality of wave segments are disposed in an alternating arrangement ofcurvature in the axial direction and in the circumferential direction.11. The compressor of claim 9, wherein at least one of the plurality ofwave segments is radially oriented toward a radially inner edge of theairfoil and at least one of the plurality of wave segments is radiallyoriented toward a radially outer edge of the airfoil.
 12. The compressorof claim 9, wherein each of the plurality of wave segments are radiallyoriented toward a radially outer edge of the airfoil.
 13. The compressorof claim 9, wherein each of the plurality of wave segments are radiallyoriented toward a radially inner edge of the airfoil.
 14. The compressorof claim 9, wherein the airfoil comprises a strut disposed in an inletregion of the compressor.
 15. The compressor of claim 9, wherein theairfoil comprises a stator vane disposed in the compressor.
 16. A gasturbine engine comprising: a compressor section; a turbine section; andan airfoil disposed in at least one of the compressor section and theturbine section, the airfoil having a trailing edge comprising ageometry having at least one wave segment including simultaneouscurvature in an axial direction and in a circumferential direction. 17.The gas turbine engine of claim 16, wherein the at least one wavesegment comprises a plurality of wave segments.
 18. The gas turbineengine of claim 17, wherein at least one of the plurality of wavesegments is radially oriented toward a radially inner edge of theairfoil and at least one of the plurality of wave segments is radiallyoriented toward a radially outer edge of the airfoil.
 19. The gasturbine engine of claim 17, wherein each of the plurality of wavesegments are radially oriented toward a radially outer edge of theairfoil.
 20. The gas turbine engine of claim 17, wherein each of theplurality of wave segments are radially oriented toward a radially inneredge of the airfoil.